Bistable watermark

Abstract

A watermark formed of a bistable material, and a method of forming the watermark, are described.

1. A material comprising a watermark area, wherein the watermark area comprises a substrate and a layer of bistable material,
 the layer of bistable material comprises areas of bistable material and areas of a filling material between the areas of bistable material, 
 the filling material comprises the bistable material and a second bistable material, the second bistable material is different from the bistable material, and 
 the filling material does not react or interact with the areas of bistable material. 
 
     
     
       2. The material of  claim 1 , wherein the bistable material of the watermark area comprises an imagewise pattern. 
     
     
       3. The material of  claim 2 , wherein the imagewise pattern is permanent. 
     
     
       4. The material of  claim 2 , wherein the imagewise pattern is permanent and hideable. 
     
     
       5. The material of  claim 1 , wherein the filling material is gelatin. 
     
     
       6. The material of  claim 1 , wherein the filling material has a different thickness than the bistable material. 
     
     
       7. The material of  claim 1 , wherein the bistable material comprises one or more of an electrochemical material, an electrophoretic material, an electro chromic material, a magnetic material, a ferro electric material, a nematic liquid crystal material, or a chiral nematic liquid crystal material. 
     
     
       8. The material of  claim 1 , wherein the bistable material comprises one or more of a nematic liquid crystal material, or a chiral nematic liquid crystal material. 
     
     
       9. The material of  claim 8 , wherein the bistable layer can be in a state selected from any bistable or gray scale state. 
     
     
       10. The material of  claim 9 , wherein the watermark area further comprises a background layer on a side of the bistable material layer opposite the substrate, wherein the background layer is the same in appearance as at least one of the states of the bistable layer. 
     
     
       11. The material of  claim 1 , wherein the watermark area further comprises a background layer on a side of the bistable material layer opposite the substrate. 
     
     
       12. The material of  claim 1 , wherein the watermark area further comprises a first conductor adjacent a first side of the bistable layer, and a second conductor adjacent a second side of the bistable layer. 
     
     
       13. The material of  claim 1 , wherein the material is paper, synthetic paper, cloth, packaging material, a tag, an electronic display, or an electronic document. 
     
     
       14. A material comprising a watermark area, wherein the watermark area comprises a substrate and a layer of bistable material,
 the layer of bistable material comprises areas of bistable material and areas of a filling material between the areas of bistable material, and 
 the filling material comprises the bistable material and a second bistable material, the second bistable material is different from the bistable material.